國立中央大學太空科學與科技研究中心
Center for Astronautical Physics and Engineering

【中大新聞】第13期:The supersonic “BOW WAVE” in the sonic boom caused by a solar eclipse: the first-time discovery made by Dr. Liu Jann-Yenq and his research team.

DRLIU“The Great American Eclipse,” the total solar eclipse on august 21, 2017, caught the world’s attention and attracted more than 1.47 million Instagramers to click like on the photo of the eclipse on NASA’s Instagram page. Dr. Liu Jann-yenq, Professor of the Graduate Institute of Space Science(GISS) at NCU and his research crew seized this opportunity and observed the supersonic motion of the Moon shadow during the solar eclipse. The supersonic motion of the Moon shadow caused a sonic boom in the ionosphere and the unprecedented “bow wave” was produced in the sonic boom. The bow wave was discovered for the first in the history. This accomplishment was published in the internationally renowned journal Geophysical Research

Dr. Liu and his team members collected data from 2,200 ground-based receivers of the Global Navigation Satellite System(GNSS) in the United States, built high spatial resolution images consisting of more than 20,000 total electron contents(TEC), and observed the solar eclipse’s influence on the ionosphere in space. They identified that during the eclipse, the Moon shadow, like a supersonic battleship, generated a sonic boom in the ionosphere, and the boom produced V-shaped ripples that moved toward two sides. The image was significantly precious.

“Since the ionospheric electric density perturbations induced by the sonic bow waves during the solar eclipse in 2017 was relatively weak, it would not really affect the systems of civil communication, positioning, and navigation. Yet the phenomenon and change of the Moon shadow during the solar eclipses are intriguing scientific issues. It is worth further examination and attention regarding how many perturbations it may cause to the Earth’s atmosphere and space environment,” said Dr. Liu Jann-Yenq.


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About 9:30 local time on August 21,2017, the supersonic Moon shadow during the total solar eclipse induced the ionospheric bow waves in the State of Oregon (and California) in the United States. (photo: Dr. Liu Jann-Yenq)


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